1. Field of the Invention
The field of the invention relates to sensors generally, and more particularly to certain new and useful advances in thermal sensor assemblies of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.
2. Description of Related Art
FIG. 1 shows a conventional thermal sensing assembly 110 in cross section. A thermal sensor element (not shown) such as a thermocouple is located within a bore 113 of a sensor tube 112 formed from thin wall deep drawn tubing having a smooth outer surface. Sensor tube 112 provides protection and positioning for the sensor element (not shown). The sensor tube 112 is rigidly connected to sensor housing 114. Sensor tube 112 and sensor housing 114 are conventionally fabricated from steel such as stainless steel or other metal as appropriate for the application environment. To provide a rigid durable connection between sensor tube 112 and sensor housing 114, the sensor tube 112 is commonly welded or machined integral to the sensor housing 114. Other methods of forming the sensing tube 112 to sensor housing 114 connection include press fitting a length of the sensor tube 112 into a smooth bore 118 within the housing 114. A threaded nut (not shown) cooperates with a threaded portion 115 of the housing 114 to retain the housing 114 onto an apparatus (not shown) having an aperture (not shown) when the threaded portion 115 is fitted within the aperture (not shown). A gasket (not shown) such as an O-ring is additionally used to provide a seal between the sensor housing 114 and the apparatus (not shown). An electrical connector 119 portion having an insulating body 128 and electrical terminals (not shown) is commonly provided as part of the sensor housing 114 to enable an electrical connection to the thermal sensor element (not shown).
In the design of a thermal sensing assembly 110 having a sensor tube 112 connected with a housing 114 it is often desirable to have a low total thermal conductivity from the thermal sensor tube 112 to the sensor housing 114. Additionally, it is desirable to have a rigid mechanical connection between the sensor tube 112 and the sensor housing 114 to prevent independent movement between the components and to ensure the assembly's 110 durability.
For at least the reasons stated above, a need exists for an improved thermal sensor device and method for assembling a thermal sensing device, having robust support for a thermal sensor and reduced thermal conductivity between the sensor and the sensor housing.